Automatic transmissions having a plurality of gear stages, which are not group shiftable, are known in many various designs. U.S. Pat. No. 5,106,352 discloses a 6-speed automatic transmission, with a simple transfer planetary gearset, is placed co-axially with a double carrier, four shaft, main-sided planetary gearset, which is designed as a Ravigneaux-planetary gearset. This design is provided with five shifting elements. Further, the transfer planetary gearset is constructed as a non-shiftable step down stage with a sun gear which is fixed to the transmission housing. The arrangement permits the output speed of rotation to be less than the speed of rotation of the input drive shaft of the automatic transmission. The output speed of rotation can be transferred by way of two clutches to two different elements of the main planetary gearset, wherein one of these two elements is fixed by a first brake to the transmission housing. This input element to the main planetary gearset, can optionally be connected to the output element of the transfer planetary gearset or fixed to the transmission housing. This input element in the following is designated as the “first input element of the main planetary gearset”. Accordingly the other input element of the main planetary gearset, which again can be connected to the output element of the transfer planetary gearset, will be known in the following as the “second input element of the main planetary gearset”. The speed of rotation of the drive shaft is directed through a third clutch to a third input element of the main planetary gearset and this third element is fixed to the housing of the transmission by a second brake. A fourth element of the main planetary gearset serves as the output element of the main planetary gearset and is exclusively, directly connected with an output shaft of the automatic transmission.
A plurality of alternative arrangements of the integral components in the automatic transmission described in U.S. Pat. No. 5,106,352 is disclosed in U.S. Pat. No. 6,139,463 and DE 102 10 348 A1.
In the unpublished DE 102 21 095.0 of the Applicant, an advanced development of the known 6-gear automatic transmission, as taught by the U.S. Pat. No. 5,106,352, is described. This development increases the number of available gears from six to seven. Further, in this development, compared to the U.S. Pat. No. 5,106,352, the transfer planetary gearset is constructed in a more simple, positive-planetary gearset in a double planetary gear construction and an additional sixth shifting element has been added. One carrier of the transfer planetary gearset forms, in this developed arrangement, an input element of the transfer planetary gearset, and is fixed to the input drive of the automatic transmission. A sun gear of the transfer planetary gearset can be fixed to the transmission housing as compared to the additional sixth gear stage of the U.S. Pat. No. 5,106,352. Correspondingly, a ring gear of the transfer planetary gearset serves as an output element of the transfer planetary gearset which output element can be connected to two different elements of the main gearset. This ring gear turns with a speed of rotation less than, or equal to, the speed of rotation of the input drive shaft. For this kinematic coupling of the individual gearset elements and shifting elements, DE 102 21 095.0 discloses a plurality of different arrangement embodiments of the transmission components wherein the components act in relation to one another.
In the JP 2001/182785A describes a further development of the 6-gear automatic transmission made known by U.S. Pat. No. 5,106,352, wherein the transmission is improved to have available an 8-gear shifting capability. Compared to the U.S. Pat. No. 5,106,352, the transfer planetary gearset now appears as a simple, non-shiftable positive-planetary gearset in a double construction and an additional sixth shifting element is added thereto. A carrier of the transfer planetary gearset forms, in this arrangement an input element of the transfer planetary gearset which is rigidly fixed to the input drive shaft of the automatic transmission. A sun gear of the transfer planetary gearset is anchored to a transmission housing. Correspondingly, a ring gear of the transfer planetary gearset forms the output element of the transfer planetary gearset. This output element can be connected with two different elements of the main gearset and always turns with a speed of rotation which is less than the speed of rotation of the input drive shaft. Compared to the U.S. Pat. No. 5,106,352, via the additional sixth shifting element, the first input element of the main gearset—can optionally be fixed with the main gearset or to the input element of the main gearset or, alternately, being anchored onto the transmission housing—can be fixed with the input drive shaft of the transmission. Taking into consideration the spatial arrangement of the shifting elements relative both to one another and to the planetary gearsets, JP 2001/182785 A proposes that the two shifting elements can be connected with the ring gear of the transfer planetary gearset, by way of the first and second input elements of the main gearset. Further, with the additional sixth element of U.S. Pat. No. 5,106,352 being axially positioned as an assembly unit between the transfer planetary gearset and the main gearset. When this is done, the situation is once again within the U.S. Pat. No. 5,106,352 known (fifth) shifting element, by way of which the input drive shaft can be connected with the third input element of the main gearset, upon the opposite side of which, this assembly unit can be placed, that is to say, on that side of the main gearset which is remote from the transfer planetary gearset. Further, the JP 2001/182785 teaches that arranging the additional sixth shifting element of the U.S. Pat. No. 5,106,352 within the component group, radially over the shifting element, by way of which the first input element of the main gearset can be connected with the ring gear of the transfer planetary gearset.
In the unpublished DE 10318565.8 of the Applicant, an improved component arrangement of the known 8-gear automatic transmission of JP 2001/182785 A is described. In relation to the basic construction of the 6-gear automatic transmission according to U.S. Pat. No. 5,106,352, in order to make only comparatively minor constructive changes, DE 103 18 565.8 proposes that the spatial arrangement of the transfer planetary gearset, with the known 6-gear automatic transmission, including the Ravigneaux main planetary gearset and the first five shifting elements being retained, while maintaining given relative locations in the transmission housing, the additional sixth shifting element is to be placed in the transmission housing on the side of the transmission proximal the driving motor axially between a transmission housing wall and a first shifting element. The output element of the transfer planetary gearset can be connected with the input element of the main gear train, via the sixth shifting element, as seen in the assembled state, between the transmission wall and the transfer planetary gearset. The additional sixth shifting element relative to the U.S. Pat. No. 5,106,352 is accordingly placed on the side of the transfer planetary gearset, remote from the main gear train.
The present invention, proposes to further develop the multi-speed automatic transmission as seen in JP 2001/182785 A and DE 103 18 565.8 to create alternate component assemblies for the planetary gearsets with eight transfer gears and the six shifting elements.